Apparatus for making prestressed honeycomb

ABSTRACT

An apparatus for forming a resilient prestressed honeycomb structure from a honeycomb structure having opposed hollow-ell faces defining opposed planar surfaces. The apparatus comprises a conveyor for conveying the honeycomb structure and a compression apparatus for compressively deforming at least a portion of the honeycomb structure. When the honeycomb structure is conveyed past the compression apparatus, the compression apparatus compressively deforms one of the planar surfaces of the honeycomb structure to form a resilient prestressed cushioned face portion. The compression apparatus comprises a plurality of parallel and elongate compression rolls for compressively deforming the honeycomb structure to form the resilient prestressed cushioned face portion. The compression apparatus further comprises a roll height adjuster for positioning the compression rolls at different heights to incrementally compress the planar surfaces of the honeycomb structure when the honeycomb structure is conveyed past the compression rolls.

RELATED APPLICATION

This application is a continuation-in-part of Ser. No. 070,097, filedMay 28, 1993 now U.S. Pat. No. 5,540,972.

TECHNICAL FIELD

This invention relates to a prestressed honeycomb structure, a methodand apparatus for forming such prestressed honeycomb structure andmanufacturing articles from such prestressed honeycomb structure and, inparticular, to a prestressed paper honeycomb structure having at leastone substantially continuous resilient cushioned face.

BACKGROUND OF THE INVENTION

One of the areas of increasing and serious public concern is thedisposal of environmental solid waste. Contributing to this disposalconcern is the growing amount of expendable packaging materials, andplastic packaging materials in particular. A large part of solid wasteconsists of plastic packaging, of which about one-third are cushioningmaterials used to support and protect relatively fragile containedarticles. One of the most common of these is expanded polystyrene.

There are numerous articles which are either nonself-supporting or whichrequire adequate cushioning support of protruding contours, edges andsurfaces to prevent damage and breakage from sideways movement or fromexternal compression and hence loss. This need is particularly great toprevent breakage and loss from shifting of electronic instruments,glass, porcelains and other like relatively delicate articles in transitor movement. Consequently, many manufacturers are looking forenvironmentally friendly, yet inexpensive, replacements which arealternatives to plastic in the area of inner packaging, in particular.

There is also an ongoing need for a lightweight, yet strong materialsuitable for filling the void space around a contained article and toprotectively cushion the article from damage during storage or shipment.This need has been fulfilled to some extent by plastic cushioningmaterials, such as moldable polyethylene copolymer, expanded foams ofpolyethylene or polystyrene, styrene acrylonitrile, and polyurethane,polyethylene air bubble packaging, polystyrene "popcorn" and "peanuts",and cellulose-based cushioning materials like curled wood shavings,popcorn, crumpled, shredded or corrugated paper and kraft honeycombstructures.

However, many of the cushioning materials are either not recyclable, oreven if recyclable, tend to be expensive and lack the combinedlightness, strength and rigidity provided by a paper honeycombstructure. Because of its great supportive strength and durability incombination with its lightness, low cost and recyclability, a paperhoneycomb structure has long been desirably employed for materialhandling and protective packaging.

Paper honeycomb structures are typically made of kraft and candistribute weight evenly to support static loads to about 12,000 poundsand dynamic loads to about 3,000 pounds. Specifically, a paper honeycombstructure provides a lower cost, thicker protective reinforcing materialwith higher strength than that provided by corrugated structures made ofcomparable kraft. The term "corrugated" is intended to refer to thewell-known reinforcing material consisting of a series of parallelelongated crests, commonly called flutes, to which inner and outer paperliners are typically secured. More importantly, a paper honeycombstructure is also a recyclable article and, thus, is a desirableenvironmentally friendly, inexpensive, lightweight and strongalternative to plastic.

In particular, void fillers and interior packaging for protectingrelatively delicate products, typically having a fragility requiringmoderate protection against about 40 to about 85 peak deceleration (G's)should desirably cushion against damage or breakage from multipleimpact. However, while biodegradable materials, including conventionalpaper honeycomb structures, generally offer adequate supportiveprotection against a single impact, they show limited protection againstmultiple impacts. For example, as a cushioning material, a conventionalpaper honeycomb structure ordinarily affords generally adequateprotection against single impacts at moderate levels of protection, butits shock absorbing characteristics for multiple impacts require moreweight and more volume than do polymeric cushioning materials.

Thus, there is still a need, therefore, for an economical protectiveresilient inner packaging material that can cushion against multipleimpacts, yet is preferably as strong, lightweight, inexpensive andrecyclable as a paper honeycomb structure. The resilient prestressedhoneycomb structure prepared by the method and apparatus of the presentinvention meets these needs.

SUMMARY OF THE INVENTION

The present invention relates to a resilient prestressed honeycombstructure comprising opposed hollow-cell faces defining planar surfacesin which at least one planar surface is substantially continuouslylaterally cushioned to a predetermined depth. Also disclosed is aone-step method and a first apparatus for simultaneously cutting andforming a resilient prestressed paper honeycomb structure in accordancewith this invention. Further disclosed is a second apparatus forincrementally laterally deforming the planar surface to form a resilientprestressed paper honeycomb structure.

The terms "resilient prestressed honeycomb structure" and "prestressedhoneycomb" are used interchangeably herein to define a paper honeycombstructure in which one of its hollow-cell faces has been substantiallycontinuously deformed along its lateral length to a predetermined depthunder the compressive conditions disclosed herein to provide it with aresilient prestressed cushioned face portion.

The cushioned face portion of the resilient prestressed paper honeycombstructure embodiment surprisingly increased the shock absorbance tomultiple impact and also reduced the amount of weight and volume ofhoneycomb structure ordinarily required for a given G-level rating ofprotection against even a single impact. Moreover, prestressed honeycombretains the desirable benefits of strength, durability, economy andrecyclability associated with paper honeycomb structures.

Resilient prestressed paper honeycomb structures can be advantageouslyprepared from conventional paper honeycomb structures which have beenconditioned prior to prestressing by the method and apparatus disclosedherein.

In a preferred method of the embodiment, the resilient prestressed paperhoneycomb structure is formed by first exposing a conventional paperhoneycomb structure of preselected thickness and length to a drying orhumidifying conditioning environment for a period sufficient tocondition the paper honeycomb structure. Briefly described, the paperhoneycomb structure is conditioned to a predetermined moisture level atwhich the paper honeycomb is judged to be compressible yet structurallysubstantially rigid and strong.

The conditioned paper honeycomb is then removed from the conditioningenvironment and thereafter can, in one step, using one of the disclosedapparatus, be simultaneously cut to a predetermined size and shape anddeformed laterally substantially continuously along one of the planarsurfaces of its hollow-cell faces to a predetermined depth to form theprestressed cushioned face portion. Alternatively, the paper honeycombcan be incrementally laterally deformed first using the other disclosedapparatus and then cut to a predetermined size or cut first and thenincrementally laterally deformed.

On release of compression, the prestressed face portion retainssufficient memory to uniformly cushion substantially all surfaces of abody in contact therewith. The surfaces of a body can be the exteriorsurfaces of articles or the walls of cartons, such as boxes for shippingand storage. The term "memory" as used herein refers to the capacity ofthe cushioned face portion of the prestressed honeycomb structure topartially recover from the depth to which it was deformed.

In various preferred embodiments, the resilient prestressed paperhoneycomb structure can include a paper face sheet secured to one orboth of its cushioned face portions either before or after beingprestressed by the disclosed method. In another embodiment, the facesheet or the partition walls of the honeycomb core comprising thehoneycomb structure may be air-permeable, such as by formingperforations therein, to allow the flow of air through the face sheet orpartition walls when the honeycomb structure is compressively deformed.

Additionally, pads of prestressed honeycomb of variable thicknesseswhich have been prestressed to the same or different depth can becombined to form custom fit inner packs which are environmentallyfriendly.

The disclosed resilient prestressed honeycomb structure offers thebenefit of a lightweight yet sufficiently strong material whicheffectively cushions against multiple impacts. Another benefit is thatthe resilient prestressed paper honeycomb structure is recyclable andinexpensive. Thus it offers the advantages of improved packageprotection and reduced size which results in a savings in storage areaand lower cost packaging combined with an environmentally friendlyrecyclable packaging.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which form a portion of this disclosure:

FIG. 1A is a perspective view of a conditioned paper honeycomb structurein the form of a pad having one face sheet illustrated before beingcompressively prestressed to a resilient honeycomb structure embodimentin accordance with the method of this invention;

FIG. 1B is a perspective view of the cushioned face portion of theresilient prestressed honeycomb embodiment formed from the pad shown inFIG. 1A.

FIG. 2A is a perspective view in partial cutaway of another conditionedand perforated paper honeycomb structure in the form of a block havingtwo opposing face sheets illustrated before being compressivelyprestressed to a resilient honeycomb structure embodiment in accordancewith the method of this invention;

FIG. 2B is a perspective view in partial cutaway of the cushioned faceportion of the resilient prestressed honeycomb embodiment formed fromthe perforated block shown in FIG. 2A;

FIG. 3 is a perspective view of a die cut press used to practice anapparatus embodiment of the present invention;

FIG. 4 is a perspective view of a die cutting tool used to practice theapparatus embodiment shown in FIG. 3;

FIG. 5 is a side view of the die cutting tool embodiment shown in FIG. 4cutting through a conditioned honeycomb structure;

FIG. 6 is a side view of the conditioned honeycomb structure seen inFIG. 5 being prestressed to form a cushioned face portion;

FIG. 7 is a perspective view of another apparatus embodiment of thepresent invention;

FIG. 8 is a side elevational view of the rear of the apparatusembodiment depicted in FIG. 7;

FIG. 9 is a side elevational view of the front of the apparatus depictedin FIG. 7, which shows a honeycomb structure, in vertical cross-section,being incrementally laterally deformed;

FIG. 10A is a side view of another conditioned paper honeycomb structurein the form of a panel having two opposed face sheets illustrated beforebeing compressively prestressed to a resilient honeycomb structureembodiment in accordance with the method of this invention;

FIG. 10B is a side view of the resilient prestressed honeycombembodiment formed from the panel shown in FIG. 10A;

FIG. 11A is an exploded elevational view of an inner packagingembodiment illustrated as a multipiece assembly of custom fit resilientprestressed honeycomb pads formed and prestressed to different depths inaccordance with the method and by the apparatus of this invention;

FIG. 11B is a perspective view of a prestressed honeycomb blankembodiment which has been score slit in two places for use as a padembodiment of the assembly of the inner packaging shown in FIG. 11A;

FIG. 11C is a perspective view of another prestressed honeycomb blankembodiment which has been score slit in three places for use as anotherpad embodiment of the assembly of the inner packaging shown in FIG. 11A;

FIG. 12 is a perspective exploded view of another inner packagingembodiment illustrated as a multipiece assembly of resilient prestressedhoneycomb pads custom fit for cushioning the surfaces of a computerprinter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For convenience, the terms "resilient prestressed honeycomb structure"and "prestressed honeycomb" will be used interchangeably to refer topaper honeycomb structures in which the planar surface of one of thehollow-cell faces has been substantially continuously deformed along itslateral length to a predetermined depth under the compressive conditionsdisclosed herein to provide it with a prestressed resilient cushionedface portion.

The terms "paper honeycomb structure" and "honeycomb core" are usedherein in their commonly understood meaning as referring to a network ofoval or generally hexagonal cells typically secured as by being glued orlaminated to one thin high strength face sheet or between two thin highstrength face sheets. The honeycomb core is a three-dimensional latticeformed by a plurality of abutting partition walls arranged in theconfiguration of a generally oval or hexagonal honeycomb pattern todefine a planar surface comprising opposed hollow-cell faces.

Paper honeycomb structures are commercially available in different sizesof core cells and thickness. For package cushioning materials, usefulcell widths can vary from about 0.25 inch (about 0.6 centimeters) toabout 1 inch (about 2.5 centimeters) and useful thickness can vary fromabout 0.25 inch (about 0.6 centimeters) to about 4 inches (about 10centimeters), but are not limited thereto. It is recognized that paperhoneycomb structures having cell widths and thickness that are larger orsmaller can be employed and still come within the scope of thisinvention so long as the honeycomb structure can form prestressedhoneycomb as disclosed herein.

Typically, the partition walls of the honeycomb core are constructedfrom paper, such as unbleached kraft, but other types of paper orpaperboard, including recycled fibers, may be employed without departingfrom the intended scope of the invention. Additionally, the hollow cellscan be resin-impregnated for water resistance and other materials suchas plastic films can also be employed if desired. As will beappreciated, the width of the cells, the height of the partition wallsor the weight of the kraft can all be varied to impart various desiredcharacteristics to the honeycomb material. Typically, at least one facesheet covers one of the hollow-cell faces of a paper honeycombstructure, but is not essential to the practice of this invention. Suchface sheets are also preferably made of kraft, though other materialssuch as plastic films, aluminum and the like can be employed.

In a preferred method embodiment, the resilient prestressed paperhoneycomb structure is prepared from a conditioned paper honeycombstructure.

A conventional paper honeycomb structure of preselected thickness andlength is first conditioned by exposing it to an environment having apredetermined ambient air temperature and relative humidity. Thisexposure is maintained for a period sufficient to dry or humidify thepaper honeycomb structure to a predetermined moisture level. Dependingon the kraft weight, a moisture level was selected at which theconditioned paper honeycomb structure was judged flexible enough to belaterally compressible along the planar surface of at least one of itshollow-cell faces yet structurally substantially strong. For simplicity,the term "conditioned honeycomb" will be used hereafter to refer to sucha honeycomb structure whether or not it includes face sheets.

In practice, a useful preferred conditioning environment was found tohave an ambient air temperature of from about 85 degrees F. (about 30degrees C.) to about 95 degrees F. (about 35 degrees C.) and an ambientrelative humidity of from about 35% to about 65%. A useful moisturelevel for the conditioned honeycomb preferably is from about 4 percentto less than about 8 percent, more preferably from about 5 percent toabout 7 percent.

The conditioned honeycomb is then removed from the conditioningenvironment and thereafter is cut and stressed preferably in one step toa predetermined size and shape to provide it with a resilientprestressed cushioned face portion. Alternatively, cutting and stressingare done in separate operations. Preferably, the conditioned honeycombis prestressed within several hours, more preferably within about anhour, of being removed from the conditioning environment.

As the conditioned honeycomb is being cut, it is simultaneously beingdeformed laterally substantially continuously along the length of theplanar surface of one of its hollow-cell faces. The deformation isachieved by compressing the selected planar surface of the conditionedhoneycomb to a predetermined depth with an apparatus having a means forsimultaneously cutting and compressing the conditioned honeycomb.Compression is then released and the resulting resilient prestressedhoneycomb is removed.

In practice, it was found that, upon releasing the compression, theprestressed cushioned face portion recovers about half of its memory toachieve the desired thickness so the depth of the compression can bereadily determined by the desired thickness of the prestressedhoneycomb. For example, to obtain a prestressed honeycomb having athickness of about 3 inches (about 7.5 centimeters), a conditionedhoneycomb structure that has a thickness of about 4 inches (about 10centimeters) is compressively deformed to about half of its originalthickness.

Any reference to the thickness of the prestressed honeycomb herein,therefore, refers to its thickness after compression is released. Inpractice, it was found that compressively deforming a conditionedhoneycomb to about half of its original thickness produced a fullydeformed honeycomb core with substantially no undeformed portion. Thistype of honeycomb core will be referred to herein as "fully cushionedhoneycomb". It was also found that compressively deforming a conditionedhoneycomb to less than about half of its original thickness provided apartially deformed honeycomb core, and surprisingly, the portion of thehoneycomb core remaining uncushioned retained substantial rigidity andstrength. The term "partially cushioned honeycomb" is used herein todescribe prestressed honeycomb core having a cushioned face portion onone of its planar surfaces and an opposed uncushioned portion.

Referring to FIGS. 1A and 1B, a pad of conditioned honeycomb 10 havingone face sheet 12 is illustrated before and after being made intoprestressed honeycomb 20. The honeycomb 10 includes a honeycomb core 15comprised of abutting partition walls 17 which form hexagonal cells 14.In this embodiment, the cushioned face portion 22 can be obtained bypartially compressing the conditioned honeycomb 10 to a thickness ofabout three-fourths of its original thickness. For example, aconditioned honeycomb pad having a starting thickness of about 4 inches(about 10 centimeters) is formed into a prestressed honeycomb pad ofabout 3 inches (about 7.5 centimeters) thickness.

For convenience and not by way of limitation, the conditioned honeycomb10 in FIG. 1A is illustrated having abutting hexagonal cells 14 each ofsubstantially uniform wall height and width to uniformly distribute anyload applied laterally to the continuous hollow cell faces.

In this type of honeycomb structure, the strength provided by thepartition walls resists compression up to a predetermined limit ofpressure, determined by the dimensions of the hollow cells and theweight of applied load. The application of a force of a predeterminedmagnitude or greater on the one face of the conditioned honeycombstructure, however, will result in the compression and deformation ofthe interior hollow cells to form a prestressed cushioned face portion.For use as an inner packaging embodiment, a cell width of about 1 inch(about 2.5 centimeters), preferably about 0.75 inches (about 1.9centimeters) or less is typically desirable but is not limited thereto.

Turning to FIGS. 2A and 2B, another conditioned honeycomb structure 110is illustrated in the form of a block having two opposed face sheets112, 116 before and after being made into prestressed honeycomb 120. Thehoneycomb structure 110, like structure 10, includes a honeycomb core115 comprised of abutting partition walls 117 which form hexagonal cells114. In this embodiment, the resilient cushioned portion 122 can beobtained by partially compressing the conditioned honeycomb structure110 to a thickness of about two-thirds of its original thickness. Forexample, a conditioned honeycomb block having a starting thickness ofabout 3 inches (about 7.5 centimeters) is formed into a prestressedhoneycomb block of about 2 inches (about 6 centimeters).

In this embodiment, the partition walls 117 and the face sheets 112 and116 may include perforations 118 to allow air trapped in the cells 114to permeate through the perforations 118 when the honeycomb structure110 is compressed. The perforations 118 allow the relief of air pressurebuild-up which occurs during compression which, on occasion, has beenknown to cause the bursting of either the walls 117, the face sheets 112and 116, or both during compression.

Preferably, each of the perforations 118 is approximately 0.125 inches(0.31 centimeters) in diameter. Preferably, the partition walls 117 ofthe core 115 include a plurality of rows and columns of perforations118. Preferably, the perforations 118 in each of the columns are alignedgenerally vertically to each other and are approximately 1 inch (2.5centimeters) apart from each other. In the embodiment of FIG. 2A, eachof the columns include three vertically disposed perforations 118 sincethe honeycomb core 115 is 3 inches (7.5 centimeters) thick. Preferably,the perforations 118 in each of the rows are aligned generallyhorizontally to each other. Although FIG. 2A shows a honeycomb structure110 wherein each of the partition walls 117 include perforations 118, itis understood that the invention encompasses a honeycomb structure 110wherein only some of the partition walls 117 include perforations 118.For example, every other sheet of paper used to make the core can beperforated with the other sheets unperforated. Preferably, perforations118 are formed in least every other abutting partition wall 117.

The face sheet 112 includes a plurality of offsetting or staggered rowsand columns of perforations 118. The perforations 118 are spaced fromeach other at predetermined distances which vary depending upon the cellsize of the honeycomb core 115. Preferably, each of the perforations 118is positioned on the face sheet 112 such that each is aligned generallycentrally with a respective cell 114 of the core 115 beneath the facesheet 112. For example, if honeycomb core with a cell size of 0.5 inches(1.25 centimeters) is used, each of the offsetting rows and columnswould include perforations 118 spaced approximately 1 inch (2.5centimeters) apart from each other. For another example, if honeycombcore 115 with a cell size of 0.375 inches (0.9 centimeters) is used,each of the offsetting rows and each of the columns would includeperforations 118 spaced approximately 0.75 inches (1.9 centimeters)apart from each other.

Not only perforated face sheets and core can be used but, additionally,face sheets and core which are constructed of an air-permeable or porouspaper can be used.

The cutting and compressing of the conditioned honeycomb is preferablymade in one step by an apparatus embodiment illustrated as thedie-cutting press 130 in FIG. 3 and the die-cutting tool embodiment 140shown in FIGS. 3-6. The die-cutting tool 140 consists of a knife 142which projects slightly above the compression plate 144 which aremounted on a support 150 in the die-cutting press 130. Knife edges, suchas serrations, perforations, and the like may be used and the depth ofthe compression can be varied by the positioning of the distance of theknife edge relative to the face of the compression plate 144. A usefulpress can be a 150 ton punch press.

As illustrated in FIGS. 5 and 6 when the die-cutting tool 140 is broughtdown upon a conditioned honeycomb structure 210, the knives 142 cutthrough its core and any face sheet present and substantiallysimultaneously compress it laterally along the planar surface of theface in contact with the moving compression plate 144 to thepredetermined depth. Thus the prestressed honeycomb 220 forms with theresilient cushioned face portion 222 and the desired shape is obtainedin one step. FIG. 3 illustrates one embodiment of a completedprestressed honeycomb panel 220 having multiple cuts 159a made by theapparatus 130 in one step. In practice, this one-step die-cut andprestressing step can be done in about 0.5 seconds, when a 150 ton punchpress is used. The cushioned face portion 222 obtained can providesubstantially uniform shock absorbance for a contacted article againstfurther applied compressive load or impact.

FIGS. 7-9 depict another apparatus, generally designated 151, forincrementally laterally compressively deforming honeycomb structure toform resilient prestressed honeycomb structure.

Referring to FIGS. 7 and 8, the apparatus 151 comprises a support frame152 including two elongate and upstanding front legs 154, two elongateand upstanding rear legs 155 and two horizontal support members 156 and157 extending transversely between the legs 154 and 155, respectively. Ahoneycomb conveyor structure 158 is secured to the lower portion of thesupport frame 152 and, more particularly, to the lower portion of thelegs 154 and 155. The conveyor structure 158 includes a pair ofhorizontal trusses 159 and 159a extending the length of the supportframe 152 and transversely to legs 154 and 155.

The ends of the truss 159 are secured to the front legs 154 while theends of the truss 159a are secured to the rear legs 155. A pair ofspaced apart and parallel rolls 161 and 162 extend between andtransversely to the trusses 159 and 159a. A conveyor belt 163 surroundsrolls 161 and 162. A horizontal support table 169, positioned below theconveyor belt 163, extends longitudinally between the rolls 161 and 162and transversely the width of the support frame 152. Each of the rolls161 and 162 is journalled for rotation on bearings 167. Each of therolls 161 and 162 has a drive sprocket 164 at one end. Although notshown in any of the figures, it is noted that drive sprocket 164 on roll161 has two parallel sets of teeth. The roll 161 includes another drivesprocket 165 at the same end including drive sprocket 164. The drivesprocket 165 has a diameter greater than the diameter of drive sprocket164. A drive chain 166 surrounds the drive sprockets 164 for connectingthe two rolls 161 and 162 together for coupled and simultaneousrotation.

A chain drive 168, associated with drive motor assembly 170, surroundsdrive sprocket 164 on roll 161. The drive chain 166 surrounds one set ofteeth on drive sprocket 164 while the chain drive 168 surrounds theother set of teeth on drive sprocket 164. According to the invention,the drive motor assembly 170 drives the chain drive 168 which drives theroll 161 which, via drive chain 166, drives roll 162 thereby causing therotational movement of conveyor belt 163.

The apparatus 151 further comprises a compression apparatus such as acompression roll frame 172 including a pair of horizontal trusses 174and 176 which extend the length of support frame 152 and between thelegs 154 and 155, respectively. The ends of truss 174 are secured to theupper portion of the two front legs 154 while the ends of truss 176 aresecured to the upper portion of the two rear legs 155. Spaced apart andparallel elongate cylindrical compression rolls 177-180 extend betweenand transversely to the trusses 174 and 176. In the embodiment shown,cylindrical rolls 177-180 have a constant radius along the full widththereof. Each of the compression rolls 177-180 is journalled forrotation on bearings 182. Moreover, each of the compression rolls177-180 may be mounted on trusses 174 and 176 so as to be verticallyindependently adjustable thereon to allow the positioning of thecompression rolls 177-180 at incrementally different heights withrespect to the horizontal table 169 and conveyor belt 163. Thecompression roll 177 may include a plurality of needles or pins 181, orother suitable puncture means, extending radially outwardly from theouter surface which allows the perforation of the face sheet 116 toimprove compression.

Attached to one end of each of the compression rolls 177-180 is a drivesprocket 184. The compression roll 180 includes another drive sprocket185 at the same end including drive sprocket 184. The drive sprocket 185has a diameter greater than the diameter of drive sprocket 184. A drivechain 186 surrounds the drive sprockets 184 thereby connecting the fourcompression rolls 177-180 together for coupled and simultaneousrotation. An idler 187 is connected to the outer surface of truss 176and is operatively associated with the drive sprocket 185 on compressionroll 180. The idler 187 includes idler gears 188 and 189, an idler pivotarm 190 and an idler spring 191. The gear 188 is connected to the end ofthe pivot arm 190 and, additionally, is connected to and operativelyassociated with the spring 191.

A chain drive 192 surrounds the drive sprocket 165 on the roll 161, thegears 188 and 189 and a portion of drive sprocket 185 on compressionroll 180. According to the invention, drive motor assembly 170 drivesthe chain drive 168 which drives the chain drive 192 which, via idler187, drives compression roll 180 which in turn, via drive chain 186,drive compression rolls 177-179.

A gib 193 is secured to each of the legs 154 and 155. Each end of thetrusses 174 and 176 is positioned within each of the gibs 193respectively to allow the vertical movement of the roll frame 172 withrespect to the support frame 152 while, at the same time, preventing thehorizontal movement of the roll frame 172 with respect to the supportframe 152.

The apparatus 151 further comprises a pair of roll height adjusters 194and 195. Each of the roll height adjusters 194 and 195 include first andsecond collars 196 and 198 fixed respectively to the horizontal supportmembers 156 and 157 of support frame 152. Each of the roll heightadjusters 194 and 195 further include first and second verticallyextending posts 200 and 202. One end of the posts 200 and 202 extendsthrough the first and second collars 196 and 198, respectively. Theother end of the posts 200 and 202 are secured to the trusses 174 and176, respectively.

Each of the roll height adjusters 194 and 195 further include anelongate and rotatable connector shaft 204 extending horizontallybetween and operatively associated with the collars 196 and 198. Amanually operable and rotatable wheel or handle 206 is connected to oneend of the shaft 204.

The manual rotation of wheels 206 causes the rotation of the shafts 204which causes the simultaneous and coupled vertical movement of posts 200and 202 which in turn causes the vertical displacement of the ends ofthe roll frame 172. The roll height adjusters 194 and 195 areindependently operable to allow for the independent and varying verticaldisplacement of the ends of roll frame 172 so that roll frame 172 may beangularly displaced with respect to the support frame 152 and thehorizontal table 169. The mechanism associated with collars 196 and 198and posts 200 and 202 for converting the rotary motion of shafts 204into the vertical movement of posts 200 and 202 may comprise anysuitable mechanism including, but not limited to, the use of a worm gearin collars 196 and 198 cooperating with teeth on posts 200 and 202.

Referring to FIG. 9, the apparatus 151, and more particularly, theadjustable roll frame 172 thereon, allows for the incremental lateralcompression of the honeycomb structure as it is conveyed past thecompression rolls 177-180 to form a prestressed honeycomb structure.Prestressed honeycomb structure is formed with the apparatus 151 asdescribed below. Initially, the roll frame 172 is positioned at apredetermined height and angle with respect to the support frame 152 andhorizontal table 169. Alternatively, each of the compression rolls177-180 may be adjusted vertically such that they are positioned atincrementally different heights with respect to the horizontal table169. Thereafter, honeycomb structure, such as the honeycomb structure110 shown in FIG. 2A, is placed on the conveyor belt 163 and thereafterconveyed by the belt 163 past the compression rolls 177-180.

Due to the angular displacement of the roll frame 172 or, alternatively,the individual adjustment of compression rolls 177-180, each of thecompression rolls 177-180 will be positioned at an incrementallydifferent height with respect to the horizontal table 169 and the topplanar surface of the honeycomb structure 110. As a result, compressionroll 177 compresses the entire top planar surface of the honeycombstructure to a first uniform depth while successive compression rolls178-180 further laterally compress the entire planar surface of thehoneycomb structure 110 to incrementally greater uniform depths untilthe honeycomb structure 110 passes through all of the compression rolls177-180 and the honeycomb structure 110 has been formed into aprestressed honeycomb structure such as the prestressed honeycombstructure 120 shown in FIG. 2B. The horizontal support table 169supports and prevents the buckling of the honeycomb structure 110 as itis compressed and conveyed through the apparatus 151. The compressionroll 177 not only compresses the honeycomb structure but preferablyalso, by means of pins or needles 181, punches perforations in thesurface of the face sheet 116 of the honeycomb structure as thehoneycomb structure is conveyed past the compression roll 177.

As an example, to form a prestressed honeycomb structure 120 having athickness of 3 inches (7.6 centimeters) from a honeycomb structure 110having a thickness of 3.5 inches (8.75 centimeters), the end of rollframe 172 adjacent the front legs 154 of support frame 152 would bepositioned approximately 2.5 inches (6.25 centimeters) away from thehorizontal table 169 at an angle A of approximately 20 degrees, withrespect to the front leg 154, such that the planar surface of thehoneycomb structure 110 is incrementally laterally deformed a totaldepth of approximately 1 inch (2.5 centimeters). Alternatively, the same1 inch incremental lateral compression can be accomplished bypositioning the roll frame 172 horizontally approximately 3.5 inches(8.75 centimeters) away from the horizontal table 169 and thenpositioning each of the compression rolls 177-180 respectively adistance of approximately 3.25, 3.0, 2.75, 2.50 inches (8.12, 7.50,6.87, 6.25 centimeters) away from the horizontal table 169. Theapparatus 151 would be positioned to deform the honeycomb structure adepth of 1 inch, rather than 0.5 inches, since a cushioned face portionrecovers approximately half of its memory, i.e., 0.5 inches (1.3centimeters) after compression.

Although the compression rolls 177-180 depicted in FIGS. 7-9 are mountedon a single integral compression roll frame 172, it is understood thateach of the rolls 177-180 may be mounted on its own separate compressionroll frame and operatively associated with four roll height adjustersrespectively, such as roll height adjusters 194 and 195, so as to bevertically independently adjustable to allow the positioning of therolls 177-180 at incrementally different heights with respect to thehorizontal table 169 and conveyor belt 163.

The apparatus 151 may be made longer than as show in FIGS. 7-9 to allowthe positioning of rolls 177-180 further apart than as presently shownto further minimize the possibility of buckling of the honeycombstructure as it is conveyed through and compressed in the apparatus 151.

The incremental lateral compression of the honeycomb structure isadvantageous because it eliminates the uneven deformation and damage tothe partition walls of the honeycomb core which occasionally resultswhen the planar surface is compressed to a predetermined depth in onestep as with, for example, the apparatus 130. The incrementalcompression allows for the gradual and incremental application ofpressure to the partition walls, thus minimizing the possibility ofuneven deformation and damage thereto. Moreover, the incremental andgradual application of pressure coupled with the formation ofperforations in the face sheet of the honeycomb structure minimizes thepossibility of bursting of the partition walls or face sheets whichoccasionally occurs when the honeycomb structure is compressed in onestep.

The apparatus 151 may be used independently of any other apparatus or,alternatively, as a modular addon component to existing lines for makinghoneycomb structure.

In FIGS. 10A and 10B, the side view of the conditioned honeycombstructure 210 is illustrated in the form of a panel having two facesheets 212, 216 before and after being fully cushioned to form theprestressed honeycomb 220. As described earlier, the fully cushionedface portion 222 can be obtained by compressing the conditionedhoneycomb structure 210 to about half of its original thickness. Forexample, a conditioned honeycomb panel having a starting thickness ofabout 3 inches (about 7.5 centimeters) forms a prestressed honeycombpanel of about 1.5 inches (about 3.8 centimeters).

A honeycomb structure for pads, blocks or panels can be composed of anyuseful kraft, bleached or unbleached, new or recycled, and any poundweight strength. For example, a useful facing sheet can be made of kraftclassified as being about 26 pound weight to about 90 pound weight and auseful cell core can be made of kraft classified as being about 26 poundweight to about 42 pound weight. The facing sheets can be secured to oneor both faces as by gluing either before the prestressing step or to theprestressed honeycomb.

Additionally, the planar surface of the resilient cushioned face portionof the prestressed honeycomb can define an irregular surface, as byleaving its honeycomb core unfaced as illustrated in FIGS. 1A and 1B.Alternatively a non-linear planar surface can be defined by angularlycompressing the honeycomb structure or by compressing it to variabledepths along its lateral axis by providing each of the rolls 177-180 ofapparatus 151 with a varying radius along the width thereof tocorrespondingly vary the depth of compression of the honeycomb structureor by further punch cutting or die cutting to provide cushioned facecavities and hinged sections. All of the foregoing still come within thescope of this invention, so long as at least a portion of the planarsurface includes a partially or fully cushioned face portion.

FIGS. 11A, 11B and 11C illustrate an inner packaging embodiment 310composed of an assembly of the four prestressed honeycomb pads, 324,326, 328, and 330, each formed and shaped from prestressed honeycomb bythe method and apparatus of this invention. By way of illustration andnot by way of limitation, the inner packaging embodiment 310 custom fitsan article A having a fragility factor in need of moderate protectionbelow a peak deceleration (G) of about 85 G.

For example, precision instruments and electronic equipment typicallyhave to be protected below a G-level rating of less than about 40 G,generally referred to as their fragility factor. Most mechanical andelectrical equipment have a fragility factor typically between about 40G and about 85 G, as discussed in more detail below.

For convenience and not by way of limitation, the article A isillustrated in FIG. 11A, in the shape of a substantially rectangularproduct, such as would be encountered with a laptop computer. In FIGS.11A, 11B and 11C, each of the prestressed honeycomb pad embodiments,324, 326, 328 and 330 are prepared from prestressed honeycomb blanks,such as 320 and 321, having the two opposed face sheets 312, 316. Forexample, useful prestressed honeycomb blanks can have face sheets madeof kraft of about 42 pound weight with a honeycomb core of about 33pound weight kraft and a cell width of about 0.5 inch (about 1.2centimeters). As illustrated in FIGS. 11A, 11B and 11C, each of theprestressed honeycomb pads can be made from a conditioned honeycombblank which is custom cut and prestressed to the desired thickness forfitting the inner packaging to the interior of the carton C, asdescribed below, without being limited thereto.

The prestressed honeycomb pads 326 and 328 are illustrated in FIG. 11Ain the form of U-shaped bumper pads each of which have been individuallyformed from a prestressed honeycomb blank, such as the prestressedhoneycomb blank 320 shown in FIG. 11B. The prestressed honeycomb blank320 is cut as a substantially oblong rectangular pad which is partiallycushioned to a thickness of about two thirds of the original thicknessof the conditioned honeycomb, for example, from about 3 inches (about7.5 centimeters) to about 2 inches (about 5 centimeters). The length ofthe blank 320 is selected so that the partially cushioned face portion322 of the bumper pad 326 contacts and protects the top T and the upperportion of the right and left sides RS, LS of the article A and that ofthe bumper pad 328 contacts and protects the bottom B and the lowerportion of the right and left sides RS, LS of the article A.

As shown in FIG. 11B, the prestressed honeycomb blank 320 has beenpartially cushioned and has also been slit scored in two places throughits uncushioned face portion to a depth sufficient for creating thehinges 318 (indicated by the dotted horizontal lines) at its cushionedface portion 322. The hinges 318 are preferably located at each endportion to form the three hinged pad sections, 320a, 320b and 320c, forforming a U-shaped bumper pad suitable for the inner packaging 310. Thehinges 318 allow each of the bumper pad sections to be folded and placedaround and with its cushioned face portion 322 in contact with thesurface of a structure, such article A as illustrated in FIG. 11A. Thus,as illustrated in FIG. 11A, the prestressed honeycomb bumper pad 326comprises the three hinged pad sections 326a, 326b and 326c ofprestressed honeycomb, the cushioned faces of which protect the top andupper surfaces of the sides of the article A and the prestressedhoneycomb bumper pad 328 comprises the three hinged pad sections 328a,328b and 328c of prestressed honeycomb, the cushioned faces of whichprotect the bottom and lower surfaces of the sides of the article A.

By way of illustration and not by limitation, when the inner packaging310 is assembled and nested in the carton C (as indicated by the arrow),the bumper pad section 326b contacts the top T, the bumper pad section328b contacts the bottom B of article A, the bumper pad section 326aabuts the bumper pad section 328a and the bumper pad section 326c abutsthe bumper pad section 328c.

The prestressed honeycomb bumper pads 324 and 330 are illustrated inFIG. 11A in the form of cap-shaped bumper pads each of which has beensimilarly formed a prestressed honeycomb blank, such as the prestressedhoneycomb blank 321 shown in FIG. 11C. For this embodiment, theprestressed honeycomb blank 321 is cut as a substantially rectangularpad which has been fully cushioned to a thickness of about half of theoriginal thickness of the conditioned honeycomb, for example, from about3 inches (about 7.5 centimeters) to abut 1.5 inches (about 3.75centimeters).

The prestressed honeycomb blank 321, as illustrated in FIG. 11C, is slitscored (indicated by the solid lines) in three places to a depthsufficient for forming the four hinged 318 prestressed honeycomb padsections 321a, 321b and 321c, which can be folded into a U-shaped capand the prestressed honeycomb pad section, 321d, which can be folded toabut against the pad section 321c. Thus, the width and length of theprestressed honeycomb blank 321 is selected and slit scored to providethe hinged cap-shaped bumper pads 324 and 330, each having four padsections as illustrated in FIG. 11A.

Thus, when the inner packaging 310 shown in FIG. 11A is fully assembledand placed in the carton C, the fully cushioned face of the pad 324aprotects the upper surface of the front face FF, and that of the pad324d protects the upper surface of the rear face RF (not shown) of thearticle A, the pad section 324b abuts against the bumper pad section326b to both further protect the top T and fill the void space at thetop and the pad 324C abuts against the pad section 324d to fill the voidspace in the rear and further protects the upper rear face RF.

Similarly, the cushioned face of pad section 330a protects the lowersurface of the front face FF and that of pad section 330d protects thelower surface of the rear face RF (not shown) of the article A, the padsection 330b abuts against the bumper pad section 328b to both fill thevoid space at the bottom and further protect the bottom B while the pad330c fills the void space and further protects the lower rear face RF,when the inner packaging is nested in the carton C.

This embodiment thus provides cushioning protection against static ordynamic loads applied over each quadrant through a 360 degree arc bothvertically and laterally.

The shock absorbance of another inner packaging embodiment was examinedin a preliminary free fall drop test. This embodiment comprised aplurality of prestressed honeycomb blocks secured as by gluing each onedirectly to one surface of a corrugated support structure. The supportstructure was then folded around a laptop computer to which a standardaccelerometer had been attached. The support structure was folded so asto place substantially all of the surfaces of the contained computer incontact with the cushioned face portions of the prestressed honeycombblocks thus providing, in effect, a substantially rectangular box-likeinner packaging lined with the prestressed honeycomb. This innerpackaging was then placed in a carton and sealed.

The carton was then attached to the drop test instrument and subjectedto a free fall drop from a height of about 1 meter and the accelerationwave form printout taken. The free fall drop test was started bydropping the carton onto one of its faces, the box was then rotated andthe drop test repeated onto another one of its faces. This procedure wasperformed using various prestressed honeycomb pads embodying theprinciples of this invention. The test was performed at an ambient roomtemperature of about 23 degrees C. and at an ambient relative humidityof about 55 percent.

The peak deceleration (G) in grams (g) and duration (D) in milliseconds(ms) as measured was found to range from G-levels of about 37 g to lessthan about 80 g at a duration of from about 19 ms to about 25 ms. Thesepreliminary results showed that the impact cushioning properties ofinner packaging made of prestressed honeycomb pads was sufficient forprotecting moderately delicate to delicate articles having a fragilityfactor rating of less than about 85 G's.

It is well known that moderately delicate electronic articles, such asstereo and television receivers, radios, and floppy disk drives have afragility factor of about 60 to about 85 G's. Delicate articles, such asaircraft accessories, electric typewriters, cash registers, computerdisplay terminals and printers and office equipment, have a fragilityfactor of about 40 to about 60 G's.

FIG. 12 illustrates another inner packaging embodiment 410 which issuitable for protecting a computer printer. This embodiment comprises anassembly of prestressed honeycomb pads, 420, 422 and 424 but is notintended to be so limited. The assembly of pads can be prepared from asingle prestressed honeycomb blank, having two face sheets, 412 and 416,each of different strengths. For example, the face sheet 412 can be ofabout 42 pound weight kraft and the face sheet 416 can be of about 26pound weight kraft with cells of about 26 pound weight kraft and a widthof about 0.5 inch (about 1.25 centimeters). As illustrated, theconditioned honeycomb can be prestressed to about 60 percent of itsoriginal thickness, i.e., from an original thickness of about 3 inches(about 77.5 centimeters to a thickness of about 1.75 inches (about 4.4centimeters).

The three prestressed honeycombs pads 420, 422 and 424 can also be diecut from a single prestressed, partially cushioned honeycomb blank bythe method and apparatus of this invention. The prestressed honeycombpad 424 is illustrated as a U-shaped base pad which has been die cutfrom a generally rectangular prestressed honeycomb blank and furtherslit scored in two places to provide hinges 418 at the cushioned faceportion 428. Thus, the base pad 424 comprises the three pad sections,424a, 424b and 424c which can be folded to form the U-shaped base pad424.

The U-shaped base pad 424 thus cushions the bottom B of the printer Pwhen it is seated in contact with the cushioned face portion 428 of thepad section 424b (indicated by the arrow). The cushioned face portion428 of the pad section 424a and the cushioned face portion 428 of thepad section 424c respectively come in contact with the front face FF andrear face RF of the printer P.

The prestressed honeycomb pad embodiments, 420 and 422, each provideside bumper pads for the printer P. Both of the side bumper pads 420 and422 can be die cut from the center portion of the prestressed honeycombblank used to form the base pad 424. In this embodiment, the side bumperpads 420 and 422 are illustrated to provide cushioning protection to thecorners of the front face FF, the sides, and outer portion of the top ofthe printer P when they are secured with their cushioned face portionsabutting against the printer after it is positioned on the base pad 424as shown by the arrows.

For example, once printer P is cradled by the U-shaped prestressedhoneycomb pad 424, the outer corners and side typically extend outsidethe periphery of pad. Thus, the cushioned face portion of theprestressed honeycomb bumper pad 422 is placed in contact with theprinter P so that the cushioned face portion 428 of the bumper padsection 422a protects the outer front face FF, the cushioned faceportion 428 of the bumper pad section 422b protects the outer portion ofthe top surface T and the cushioned face portions of the bumper padsections, 422c, 422d and 422e protect the left side portion LS.

Likewise, the bumper pad 420 is positioned so that the cushioned faceportion 428 of the bumper pad section 420a protects the opposed outercorner of the printer P. Thus, the cushioned face portion 428 of thebumper pad section 420b protects the opposed outer top portion, and thecushioned face portions of 420c, 420d and 420e protect the right side RSof the printer P.

As illustrated, the bumper pads 420 and 422 have been die cut and hingedto provide four vertical cushion pads and one horizontal cushion pad. Ascan be appreciated, the shape of the prestressed honeycomb assembly isnot limited and can be modified as desired and still come within scopeof this invention, as long as all of the pads have cushioned faceportions and are in contact with the structure to be protected.

The shock absorbance of another inner packaging embodiment suitable forsimilarly protecting a printer was determined for two units using thefree fall drop test described above. The preliminary results werecompared against those obtained for two similar size inner packagingunits of expanded polystyrene (EPS) foam subjected to the same test. Theresulting G ratings from multiple impacts were as follows for the EPSand prestressed honeycomb (PH).

    ______________________________________                                        Face         EPS               PH                                             Tested       Unit 1  Unit 2    Unit 1                                                                              Unit 2                                   ______________________________________                                        Right Side   40      36        36    57                                       Left Side    42      39        35    88                                       Front        60      56        37    49                                       Rear         72      75        57    76                                       Bottom       83      98        87    67                                       Top          98      92        42     94*                                     Average G Rating                                                                           66                60.5                                           ______________________________________                                         Note *Top Corner Pad twisted off                                         

These preliminary results showed that, on average, the prestressedhoneycomb inner packaging provided cushioning protection againstmultiple impacts comparable to or better than foam inner packaging. Infurther tests, prestressed honeycomb has been found to be superior tofoam cushioning material.

Methods for determining the shock absorbing characteristics ofmaterials, such as honeycomb structures, are generally found in ASTMD1596 (Standard Test Method for Shock Absorbing Characteristics ofPackage Cushioning Materials) and are well known to those skilled in thematerial testing arts. Cushion curves obtained by these methods relatethe peak deceleration (G) experienced by the cushioned weight in a freefall drop to the static loading S defined as S=W/A; where W is theweight of the product and A is the support area underneath the weight(contact area between the weight and cushion). The curves are normallypresented in graph form with peak deceleration (G) on the vertical axisand static loading (psi) on the horizontal axis.

Materials that show good shock absorbance have lower G values, and lessdense materials are principally preferred. Once the stressed honeycombis made, it can be further cut, or score slit to form a hinge, or befurther punch cut at a preselected section to provide a prestressedprotrusion point cushion. The resilient prestressed paper honeycombstructure can be cut in the shape of a pad, block or panel.

It has been found that cushioning protection is greater when thehoneycomb structure is stressed to a depth of less than about half ofits original thickness to provide it with a partially cushioned faceportion. Additionally one of the resilient prestressed honeycombstructures can be further abutted against a second resilient prestressedhoneycomb structure which has been prestressed to the same or differentdepth if desired for obtaining various levels of cushioning protection.

Additionally, the resilient prestressed honeycomb structure can be cutand formed to any size and shape in one step by the method and apparatusof this invention to provide a lightweight strong inner packaging havingone or all of its planar surfaces cushioned. This beneficially providessubstantially uniform cushioning protection of articles having afragility factor rating of less than about 85 G's against multipleimpacts.

Moreover, the foregoing inner packaging can also be formed with cavitiesof nearly any shape to custom fit products of various configurations andweights with the added advantage of substantially uniformly cushioningall of the surfaces of the product. Until now, the benefits of innerpackaging made of paper honeycomb structures having such continuouslyresilient prestressed surfaces was not available.

Additionally, the resilient prestressed honeycomb structure can besecured directly to the surface of the interior walls of cartons, boxesand the like, with its cushioned face portion facing inwardly orabutting the interior walls. Alternatively, the resilient prestressedhoneycomb structure can be inserted, such as in pad form, between anarticle and the wall of the carton or box in which it is contained toprovide cushioning protection to substantially all surfaces.

The foregoing is illustrative of the principles of the invention.Further, since numerous modifications and changes will readily occur tothose skilled in the art, it is not desired to limit the invention tothe exact construction and operation shown and described. Accordingly,all suitable modifications and equivalents may be resorted to whilestill falling within the scope of the invention.

What is claimed is:
 1. An apparatus for cutting and forming a resilientprestressed paper honeycomb structure of a predetermined size and shapein one step, the apparatus comprising:a) means for cutting through apaper honeycomb structure comprising opposed hollow-cell faces definingplanar surfaces along a predetermined line to form a predeterminedshape; b) at least one plate cooperatively associated with the cuttingmeans, the plate being capable of compressing the paper honeycombstructure substantially continuously along at least one of its planarsurfaces to form a resilient prestressed cushioned face portion; and c)means for simultaneously driving the cutting means through the honeycombstructure while laterally compressively deforming the selected planarsurface to a predetermined depth, such that a prestressed honeycombstructure having a substantially continuous resilient cushioned planarsurface is obtained.
 2. The apparatus of claim 1 wherein the platecompressively deforms the selected planar surface to a uniformpredetermined depth to form a substantially linear cushioned faceportion.
 3. The apparatus of claim 1 wherein the plate compressivelydeforms the selected planar surface to a non-uniform predetermined depthto form a non-linear cushioned face portion.
 4. An apparatus for forminga resilient prestressed honeycomb structure comprising:a) a conveyor forconveying a honeycomb structure including opposed hollow-cell facesdefining opposed planar surfaces; and b) a compression apparatus forcompressively deforming at least a portion of one of the planar surfacesof the honeycomb structure to form a resilient prestressed cushionedface portion as the honeycomb structure is conveyed past the compressionapparatus.
 5. The apparatus of claim 4, wherein the compression meanscomprises a compression roll with a varying radius along the widththereof for forming a cavity in a portion of one of the planar surfacesof the honeycomb structure.
 6. The apparatus of claim 4, wherein thecompression means comprises a cylindrical compression roll having aconstant radius along the width thereof for laterally compressivelydeforming the entire one of the planar surfaces of the honeycombstructure.
 7. The apparatus of claim 6, further comprising means forvarying the height of the compression roll with respect to the conveyorto vary the depth to which the one of the planar surfaces iscompressively deformed.
 8. The apparatus of claim 6, wherein thecompression roll includes a plurality of pins extending radiallyoutwardly from the outer surface thereof for forming perforations in thehoneycomb structure as the honeycomb structure is conveyed past thecompression roll.
 9. The apparatus of claim 4, wherein the compressionapparatus comprises a plurality of parallel compression rolls positionedabove the conveyor and the honeycomb structure, each of the compressionrolls being positioned at an incrementally different height with respectto the conveyor for incrementally laterally compressively deforming theone of the planar surfaces of the honeycomb structure as the honeycombstructure is conveyed past the compression apparatus.
 10. The apparatusof claim 9, further comprising a roll frame supporting the compressionrolls and means for adjusting the height and angular displacement of theroll frame with respect to the conveyor such that the compression rollsare positioned at incrementally different heights with respect to theconveyor for incrementally laterally compressively deforming the one ofthe planar surfaces of the honeycomb structure.
 11. The apparatus ofclaim 10, wherein the means for adjusting the height and angulardisplacement of the roll frame comprises a roll height adjusteroperatively associated with the roll frame for adjusting the height andangular displacement of the roll frame.
 12. The apparatus of claim 11,wherein the roll height adjuster is operatively associated with one endof the roll frame for adjusting the height of the one end of the rollframe, the apparatus further comprising another roll height adjusteroperatively associated with the other end of the roll frame foradjusting the height of the other end of the roll frame.
 13. Theapparatus of claim 10, further comprising means on the roll frame forindependently adjusting the vertical position of each of the compressionrolls.
 14. The apparatus of claim 10, further comprising a support frameand a plurality of gibs secured to the support frame, the roll framebeing supported within the gibs to allow for the vertical movement ofthe roll frame with respect to the support frame.
 15. An apparatus forforming a resilient prestressed honeycomb structure comprising:a) asupport frame; b) a belt for conveying a honeycomb structure, thehoneycomb structure including opposed hollow-cell faces defining opposedplanar surfaces; c) a roll frame positioned above the belt, the tollframe being mounted for pivotal displacement about the support frame; d)a plurality of parallel and elongate compression rolls mounted on theroll frame for compressively deforming at least a portion of one of theplanar surfaces of the honeycomb structure to form a resilientprestressed cushioned face portion as the honeycomb structure isconveyed past the compression rolls; and e) a roll height adjustersecured to the support frame and operatively associated with the rollframe for varying the vertical and angular displacement of the rollframe with respect to the support frame and positioning the compressionrolls at different heights with respect to the support frame such thatwhen the honeycomb structure is conveyed past the compression rolls, thecompression rolls incrementally compress at least a portion of one ofthe planar surfaces to a predetermined depth to form the resilientprestressed cushioned face portion of a prestressed honeycomb structure.16. The apparatus of claim 15, further comprising gibs secured to thesupport frame, the roll frame being supported within the gibs to allowvertical and angular displacement of the roll frame with respect to thesupport frame.
 17. The apparatus of claim 15, wherein the roll heightadjuster is operatively associated with one end of the roll frame forvarying the height of the one end of the roll frame, the apparatusfurther comprising another roll height adjuster operatively associatedwith the other end of the roll frame for varying the height of the otherend of the roll frame.
 18. The apparatus of claim 15, further comprisingmeans on the roll frame for independently adjusting the verticalposition of each of the compression rolls.
 19. The apparatus of claim15, further comprising a connector shaft and an adjustment wheeloperatively associated with the roll height adjuster, the connectorshaft being connected at one end to the roll height adjuster and at theother end to the adjustment wheel, the adjustment wheel being manuallyoperable for adjusting the height of the roll height adjuster.
 20. Theapparatus of claim 15, wherein each of the compression rolls iscylindrical and has a constant radius along the width thereof forlaterally compressively deforming the entire one of the planar surfacesof the honeycomb structure.
 21. The apparatus of claim 15, wherein eachof the compression rolls has a varying radius along the width thereoffor forming a cavity in a portion of one of the planar surfaces of thehoneycomb structure.